<template>
        <h1>子组件</h1>
        <h1>{{ modelValue }}</h1>
        <button @click="emit('update:model-value',modelValue+1)">
            点击传参
        </button>
</template>
<script setup>
    // 1.接收
        defineProps({
            modelValue:Number
        })
    // 2.发送 
    // let emit = defineEmits(['update:modelValue'])
    let emit = defineEmits(['update:model-value'])
    // 注意：modelValue可以写成model-value
</script>
<style>
.box {
    min-height: 200px;
    border: 1px solid #000;
    padding: 20px;
    box-sizing: border-box;
}
</style>